Production of acid free flowers of sulphur



. A. C. MOHR Filed Sept. 50, 1939 Nov. 26, 1940.

PRODUCTION OF ACID FREE FLOWERS OF SULPHUR IIU Patented Nov. 26, 1940'UNITED STATES PATENT oFF ce PRODUCTION OF ACID FREEFLOWERS F SULPHURAlbert 0. Mohr, Berkeley, cane, assignor to San Francisco SulphurCalifornia Company, a corporation of Application September 30, 1939,Serial N 0. 297,321

2 Claims.

into a mass, have an acid content as sulphuric acid of 0.4% to as muchas 2.5%. In addition, only about 50% of the material collected in thechamber is in such a form that it can be classified as flowers ofsulphur, the remainder of the sulphur being in undesirable grades ofgranulated pile sulphur and rock sulphur.

In accordance with this invention, I am able to increase the yield offlowers of sulphur collecting in the chamber to the order of 75% at theexpense of the undesirable granulated pile'and rock sulphur produced. Inactual operation I have been able to reduce the granulated pile sulphurproduced to approximately 24% and the rock sulphur to about 2.5%. At thesame time the acid content of the sulphur is reduced to 0.15% and lessas sulphuric acid.

I have discovered that by first heating the sulphur to remove or reducethe'oxygen content initially present in the atmosphere of the condensingchamber the acid content can be reduced. If the heating is thencontinued and sulphur vapor thereafter is jetted into the condensingchamber, preferably through a plurality of jets, the beneficial resultstypifying the present invention will be secured. I appreciate that ithas heretofore been proposed to utilize an initially inert atmosphere inthe condensing chambersee British Patent No. 7,086 of 1898. However,while it is quite easy for one to say employ an inert atmosphere in thecondensing chamber, in practice it is something else and, so far as I amaware, the practice of the British patent has never been employedcommercially.

I have discovered that if the atmosphere of the chamber is initiallydeprived of its oxygen by burning of the atmosphere with sulphur in sucha manner that the temperature of the flame does not exceed 900 C., andis not what is known in the trade as high intensity burning, then theacid content of the sulphur will be reduced. This low intensity burningis continued until combustion of the sulphur is no longer supported. Thesulphur vapor is then discharged into the now oxygen-lean atmosphere ofthe chamber, preferably through a plurality of nozzles, and condensed toform the acid free flowers of sulphur. While I have not proven this, areasonable explanation appears to be that when high intensity burning ispermitted, nitric oxide is formed aswell as sulphur dioxide. Theconditionsare such that in efiect one has a flead chamber process forthe production of sulphuric acid. By operating at a temperature whereatthe flame temperature is below about;900.C. nitricoxide formation isprevented and, asa consequence, the so-called acid contentof the flowersof sulphur is reduced'to 0.15% sulphuric acid andless. r

It is in general the broad object of the present invention to provide animproved process for the manufacture of flowers of. sulphur. v

Another object of 'thepresent inventionis to provide for manufacture offlowers of sulphur substantially free of acid in a condensing cha nberemploying ordinary air as the condensing medium;

A further object of the present invention is to provide a suitableapparatus enabling the production of flowers of sulphur, and the yieldthereof, to be improved. The invention includes other objects andfeatures of advantage, some of which, tog'ether with theforegoing, willappear hereinafter wherein a practice illustrating the preferred mannerand apparatus" of the'invention is disclosed.

In the drawing, Figure 1 is a "diagrammatic view illustratingtheapparatus arrangement which can be typically practiced.

Figure 2 is a section through the gooseneck outlet while Figure 3 isa,plan view of the orifice plate employed. In the drawing I have shown asuitable furnace l heated by a burner 8 and discharging gases ofcombustion'through" flue 9 into a stack ll. A sulphur melting pct 12 isheated by the gases of combustion passing-through flue 9. Melted sulphuris discharged through line I3 into goosei neck M on a sulphur vaporizingvessel l6 positioned in the furnace 1. Adjacent to the furnace is acooling chamber indicated generally by'numeral l1. As is well knownin'th-e art, this is a relatively large brick chamber. Gooseneck l4discharges into chamber I! adjacent one end thereof and intermediate thetop and bottom and usually centrally of the width.

In operation, liquid sulphur is delivered through pipe I3 into gooseneckI4 and thence into vessel I6. In vessel l6 sulphur is first maintainedabove its kindling temperature (260 C.) and below that temperature atwhich any appreciable quantity is discharged into chamber I'L After theoxygen in chamber I! is exhausted the sulphur is ejected into chamber l!by being heated to above its boiling point, 444.6 C.

It is commonly stated that sulphur is sublimed, but this is not strictlycorrect, because sulphur does not pass from the solid to the vapor statedirectly. The kindling temperature of sulphur is below its. boilingpoint, about 260 C. As the sulphur is heated in vessel 16, if any oxygenbe present suflicient to support combustion, the sulphur burns. Now itis my observation that with the operation of the structure of the Cecconapplication, direct release of the jet of sulphur vapor into the airfilled atmosphere of the condensing chamber caused a high intensityflame adjacent the nozzle through which the jet was released and,correspondingly, a relatively high acid content.

This high intensity flame is also secured in the operation of such aprocess as that shown in the French Patents No. 567,658 and No. 574,573and in the U. S. patent to Walters No. 873,812 of December 17, 1907, andin the U. S. patent to Reed No. 1,518,126 of December 2, 1924. In these,air is blown over the molten sulphur or into contact with hot sulphurvapor. Not only are these processes objectionable in that the heat ofthe sulphur is transferred to the atmosphere in the condensing chamberand the temperature of the chamber .raised but, additionally, thepractically unrestricted air-sulphur contact creates a high intensityflame with consequent formation of flowers of sulphur of high acidcontent.

In accordance with this invention, I. permit initial free access of theatmosphere of the condensing chamber I! with sulphur undergoing heatingand vaporizing in vessel Hi. This is possible because ordinarily thegooseneck has a relatively large cross-sectional area, the gooseneckwhich I employ having a diameterof 14 inches. Since the gooseneck has arelatively small volume as compared to the chamber, and since whatevercirculation occurs in the gooseneck is due largely to convection, theair quantity available to the sulphur at any instant is relativelysmall. The sulphur therefore cannot burn rapidly. As a consequence, alow intensity flame is present in the gooseneck. If desired, a suitablesight opening and glass may be provided to observe this flame in thegooseneck. When the oxygen content in the chamber I1 is so low that itwill no longer support combustion, as determined either by the usualpyrogallol test, or else by actual observation of the conditions in thegooseneck, I lower nozzle plate l8 into position. The discharge end 2|of the gooseneck I4 is at an angle of about 45 to the vertical and theplate 18 is hinged above it as at 22. A cable 23 extends from ears 24 toa winch indicated generally at 26. The plate carries a plurality oforifices 21 preferably of a relatively small size and I have used aplate on a 14 inch diameter gooseneck having 12 1-inch pieces ofstainless steel pipe. The plate carries a seating ring 28 cooperatingwith a gasket 29 to ensure tight seating so that all sulphur vapor isemitted through the nozzle in the plate. The weight of the plate holdsit snugly in place.

With continued and possibly increased heating the sulphur vapor is thendischarged upwardly into the oxygen-lean atmosphere of the chamber, inwhich the oxygen content has been reduced to an extent suflicient thatthe atmosphere will no longer support combustion with the sulphur.Usually an atmosphere containing less than 10% oxygen is. too lean toburn with sulphur. The plate is left in position until the run iscompleted.

At the commencement of a new run, after the chamber has been open, theplate is lifted out of position so that free access of the chamberatmosphere to the sulphur undergoing vaporizing in chamber Hi can occurand the oxygen be removed therefrom.

It is to be noted that plate [8, when in position, is at an angle ofabout 45. The eifect of this, and of the plurality of jets, is todischarge the sulphur vapor upwardly and ensure that adequate andthorough mixing of the sulphur vapor with the inert, cold atmosphere ofthe chamber ll occurs. This is particularly advantageous in reducing theamount of rock sulphur produced and increasing, at the expense of therock sulphur, the yield of flowers of sulphur.

This case is a continuation-in-part of application Serial Number 191,581filed February 21, 1938.

I claim:

1. In a process for producing substantially acid free flowers of sulphurwherein a mass of sulphur is heated in a vessel and vaporized in saidvessel and finally discharged as a vapor at substantially the pressureexisting in said vessel into a chamber filled with a cold gaseousatmosphere initially containing oxygen sufficient to support sulphurcombustion, the improvement which includes the steps of heating saidsulphur mass in said vessel to a temperature of 260 C. and below 445 C.while permitting substantially free access of the chamber atmosphere tosaid mass in said vessel to consume oxygen in the chamber atmosphere bycombustion immediately adjacent to the sulphur mass in said vessel witha flame of relatively low temperature, as compared to the flametemperature when the sulphur is vaporized directly into the chamber andburns therein away from said mass and in contact with the combustionsupporting oxygen containing atmosphere of said chamber, and continuingheating of the mass until the oxygen content of said chamber atmosphereis diminished to an extent such that said chamber atmosphere will notsupport further sulphur combustion while said chamber is substantiallyfree of any sulphur discharge from said mass, and then heating thesulphur to a temperature of at least 445 C. to discharge vaporizedsulphur from said mass into said chamber.

2. In a process for producing substantially acid free flowers of sulphurwherein a mass of sulphur is heated in a vessel and vaporized in saidvessel and finally discharged as a vapor at substantially the pressureexisting on said vessel into a chamber filled with a cold gaseousatmosphere initially containing oxygen suflicient to support sulphurcombustion, the improvement which includes the steps of heating saidsulphur mass in said vessel to above substantially its kindlingtemperature and. below substantially that temperature at which sulphurvaporizes rapidly from the mass in said vessel and passes over anddischarges from said vessel into said chamber while permittingsubstantially free access of the chamber atmosphere to said mass in saidvessel to consume oxygen in the chamber atmosphere by combustionimmediately adjacent to the sulphur mass in said vessel with a flame ofrelatively low temperature, as compared to the flame temperature whenthe sulphur is vaporized directly into the chamber and burns thereinaway from said mass and in contact with the combustionsupporting oxygencontaining atmosphere of said chamber, and continuing heating of themass until the oxygen content of said chamber atmosphere is diminishedto an extent such that said chamber atmosphere will not support furthersulphur combustion While said chamber is substantially free of anysulphur discharge from said mass, and then heating the sulphur toboiling to discharge vaporized sulphur from said mass into said chamber.

- ALBERT C. MOHR.

